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प्रश्न
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उत्तर
We can find the relative density of a solid which floats on water by following the experiment.
Measuring the relative density of a cork
Choose a sinker and find its weight in water by suspending it in water.
Tie the solid to the string attached to the sinker and find its weight in air but sinker in water.
Remove the solid and tie it together with the sinker and suspend it in water and find the weight of the solid together with the sinker in water.
Record your observation as shown below:
Weight of sinker in water = x gf
Weight of sinker in water + solid in air = y gf
Weight of solid in air = (y - x) gf
Weight of solid + sinker in water = z gf
upthrust on solid in water = (y - z) gf.
The upthrust on in water also represents the weight of the water displaced by the solid. Relative density of solid = (weight of cork in air )/(weight of equal volume of water) Relative density = (y - x)/(y - z).
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संबंधित प्रश्न
A body is held immersed in a liquid. (i) Name the two forces acting on the body and draw a diagram to show these forces. (ii) State how the magnitudes of two forces mentioned in part (i) determine whether the body will float or sink in liquid when it is released. (iii) What is the net force on the body if it (a) sinks and (b) floats?
When a piece of wood is suspended from the hook of a spring balance, it reads 70 gf. The wood is now lowered into water. What reading do you expect on the scale of spring balance?
A block of wood is so loaded that it just floats in water at room temperature. What change will occur in the state of floatation, if
(a) Some salt is added to water, (b) Water is heated?
Give reasons.
For a floating body, its weight W and upthrust FB on it are related as :
A body floats in a liquid A of density ρ1 with a part of it submerged inside the liquid, while in liquid B of density ρ2 it is totally submerged inside the liquid. The densities ρ1 and ρ2 are related as :
A weather forecasting plastic balloon of volume 15 m3 contains hydrogen of density 0.09 kg m-3. The volume of equipment carried by the balloon is negligible compared to its own volume. The mass of an empty balloon alone is 7.15 kg. The balloon is floating in air of density of 1.3 kg m-3. Calculate:
(i) The mass of hydrogen in the balloon,
(ii) The mass of hydrogen and balloon,
(iii) The total mass of hydrogen, balloon and equipment if the mass of equipment is x kg,
(iv) The mass of air displaced by balloon and
(v) The mass of equipment using the law of floatation.
A cube of ice whose side is 4.0 cm is allowed to melt. The volume of water formed is found to be 58.24 cm3. Find the density of ice.
Name an instrument based on this principle. State two uses of the instrument that you describe.
How does an object’s density determine whether the object will sink or float in water?
